Means for preventing crust formations on the walls of boilers



May 31, 1938. P. s. MAZZA 1 ,9

MEANS FOR PREVENTING CRUST FORMATION S ON THE WALLS OF BOILERS FiledJuly 3, 1934 Patented May 3.1, 1938 UNITED STATES' PATENT OFFlCE- MEANSFOR PREVENTING oaUs'r roar muons N 'rna WALLS or normas Plinio SergioDavide Mam. Paris, France- I .Applicaiionluly a. 1934. Serial No.733,692

I In France July-19, 1m

4 Claims. .(Cl. 2iM-25) My invention relates to means for protecting thewalls of steam boilers or similar apparatus against scales,incrustations and corrosions.

It has already been proposed, for preventing 5 the formation ofboilerscales, to apply a source of electric current for causing, theneutralization cathodes of thermionic tubes. When said electrons havemoved out of the metal, said metal trons at an infinitely small distanceaway from the wall. The negative charges of said electrons act upon thepositive charges of the anions of salts and acids which are dissolved inthe water of the boiler and, attract the same towards the wall. Theequilibrium between all those forces is realized when anions havereached the wall upon which they strongly adhere. The positive chargesof the wall act in the same manner upon the cations. The equilibrium orcancellation of charges is realized when said cations have placedthemselves above the bed of anions. All charges being cancelled, themetal continues emitting electrons and the above described phenomenonoccurs again indefinitely.

The method according to my invention consists, providing in theseveralparts of the steam boiler or similar apparatus in which incrustationsare to be prevented, electric charges which are equal influence of atemperature increase. Hie invention also provides for passing pulsatingcurrent or preferably alternating current through the acquires apositive charge which keeps the elecs gr m lly represented at I.

but opposite to those which appear under the' embodiment of plant whichrealizes the method according to my invention:-

Fig. 1 is a diagram showing a simple arrangement for performingthemethod according to my invention, 5

Fig. 2 diagrammatically shows another arrangement,

Fig. 3' diagrammatically shows the arrangement of the circuits whichlead the electric cur- 10 rent through the boiler,

Fig. 4 diagrammatically shows the arrangement of the plant with a boilerwhich is in a position to receive electric charges from an externalsource,

Fig. 5 is a diagrammatic view illustrating the 15 movebie ,inounting ofthe transformer secondary. In Fig. 1, the boiler or similar apparatus inwhich incrustations are' to be prevented, is dia- On opposite ends ofthe boiler, and in conveniently deter- 20 mined points of same, areconnected the terminals of an electric circuit which include thesecondary winding 2 of a transformer. The transformer may be providedwith a magnetic core, and the primary 3 is connected with the 5terminals of a source of alternating current 6 of any voltage andfrequency. -The approximate mid-point. of the secondary 2,0! thetransformer 'is electrically connected with a potentiometer l which isfed by a source 5 of direct current hav- 30 ing a suitable voltage. Bothwindings 2 and I of the transformer are magnetically coupled with eachother and the winding 2 is movable relatively to the winding 3, in orderthat, the electro-dynamic reactions between the coils which 35 arecreated in both windings, may automatically vary according to thecurrent which flows in the same; The windingl is brought back to itsresting position by any suitable means, for instance by gravity or bythe action of a direct electric 40 field. The secondary winding 2 ismechanically connected with the arm of the potentiometer I.

Fig. 5 illustrates a suitable arrangement wherein the secondary windingis movable relative to the primary winding. The primary winding 3 isstationary and the secondary winding 2 may slide along the magnet core,3). The weight of the secondary winding is balanced by thecounterweight 34 connected therewith bymean's of a flexible wire ll, thelatter passing around a pulley g 36 which actuates a cam 31; The cam 3!acts. upon a cbntact arm 38 of the potentiometer 4.- The circuit whichpermits electric current to how throughthe boiler is arranged in suchamanner that the several parts of said boiler are charges which areequal and opposed to. the nat-' ural charges occurring in said boiler.Thus the electric field which keeps theelectrons near the boiler wall iscancelled and the electrons are attracted far away from the wall by theanions of salts. The charges of the electrons are cancelled. and thesalts which precipitate deposit themselves on the bottom of the boilerin the form of a mud which does not adhere to the metal.

Furthermore, the alternating current has a disintegrating efiect uponthe first layers of scale, because it communicates a vibratory movementto the molecules which adhere to the walls and moreover said vibrations,the amplitude of which is a function of the voltage, are larger in thehotter points which are more susceptible to scaling or incrustations.

The current which flows through the boiler is maintained constant as aresult of the self regulation obtained with the transformer 2. 3. Eachchange of working conditions in the boiler causes a change of voltage atthe terminals of the secondary I of the transformer, and acorresponding' change of voltage. due to the modification of flux andthe displacement of said secondary winding relatively to the primarywinding by reason of theelectro-dynamical reactions between the currentswhich flow in bothwindings. The reactions are balanced as abovedescribed, either by the weight of winding 2 or by a direct currentmagnetic field, or a counterweight as shown in Fig. 5.

Owing to the fact that the winding 2 is mechanically connected with thearm of the potentiometer l, the self regulation applies also to thedirect current voltage supplied to the boiler.

Since the electrical resistance of metal increases with the temperatureand since the circuit which feeds the boiler with current is arranged insuch a manner that all its'parts are connected in series and in an ordercorresponding to their increasing temperature, a second regulation willthus be obtained and hence the hottest metallic parts which emit thelarger quantity of electrons will receive a higher voltage, so that thecharges which occur in said parts of the boiler will always be exactlybalanced or destroyed.

Fig. 2 diagrammatically shows another embodiment which is more adaptableto cases when the boiler or other similar apparatus may be submitted todifi'er'ences of potential, as for example boilers of locomotives whichroll on a rightof-way of an electrified railway line and where a currentof a high intensity flows in the rails. In this modification, the sourceof. current 6 is still connected with the primary winding 3 of atransformer. The secondary winding 2 isadapted to be rotated relative tothe primary.

A rectifier I enables the alternatin current of source 6 to betransformed into a direct current, said current being suitably filteredby a choke coil 8 and condensers 9. Said direct current passes intothepotentiometer l the arm of which is still connected with middle partof the secondarywinding 2.

Thesecondary 2 is connected with the windings i0 and H, one of which,for instance the winding ll, may be variablycoupled with a third windingis in a manner similar to that described in connection with winding 2relative to the winding 3. The coil I2 is connected across thepotentiometer 4 so that direct current flows therein. The winding H ismechanically connected with the arms of two potentiometers i3, ll, inwhich also flows a direct current coming from the rectifier. Thewindings II, II, and the potentiometers l3, ll, are adapted to beconnected with the boiler at Ii. The coupling of windings 2, 3 of thetransformer may also be modified as in the preceding embodiment, so thatthe changes of voltage, also cause the operation of the potentiometer 4.

If a current flowing in the boiler is in a position to trouble or evento cancel the current which is sent by the winding I, the current whichfiows through winding il induces therein a field which reacts upon thefield produced in winding ii. If the current is alternating and withoutany effect upon the scaling phenomena of the boiler, the couplingbetween the windings Ii and I2 is not altered which leaves thepotentiometers II, II, in com position. If such current is direct. thefield of the winding ll reacts upon. the field of winding l2 andmodifies the coupling between both of said windings and consequentlyoperates the potentiometers l3 and I4 so as to cause the boiler toreceive a current which cancels the occasional current which was flowingthrough the same.

' Fig. 3 diagrammatically shows the 'eie'otrie" ment of a boiler 2|mounted in the hull of a ship and electrically connected with the hullII and consequently with the sea 22. This arrangement has the drawbackinthat the appearance of charges-upon the boiler walls causes a current totake place, which may oppose the effects of the current employedaccording to my method. For remedying this drawback, auxiliary currentsources 23 are located in suitable determined places. Such sources havea suitable voltage for producing a current, which is opposite to thecurrent, towards 'the boiler from the hull.

The arrangement of the several parts of boilers which are locatedrinseries in the circuit is obtained by the tentative method and obviouslydiifers according to the type of boiler.

The plant may be provided with thermionic lamps for regulating thecurrent sent into the boiler.

My invention applies for preventing incrustations and corrosions ofboilers or similar apparatiisofanytypeandforanyuse.

What I claim is:--

1. Means for protecting the walls of boilers of the secondary winding tosaid potentiometer to vary the adjustment of the latter.

2. Means for protecting the walls of boilers and similar apparatusagainst scale, incrustations and corrosions, comprising a transformerincluding primary and secondary windings, a boiler connected with saidsecondary winding, a potentiometer connected with the central point ofsaid secondary winding, said secondary winding being movable relativelyto the primary winding in response to temperature difierences in saidboiler, and means for transmitting movement of said secondary winding tosaid potentiometer to vary the adjustment of the latter.

3. Means for protecting the walls of boilers,'

and similar apparatus against scale, incrustations and corrosionscomprising a boiler, a transformer including primary and secondarywindings, the secondary winding being connected with said boiler andbeing movable relative to the primary winding, means for impressing anelectric charge on said boiler, and means connecting said movablesecondary winding with said charge impressing means to regulate thelatter.

4. Means for protecting the walls of boilers,

v and similar apparatus against scale, incrustations and corrosionscomprising a boiler, a transformer including primary and secondarywindings, the secondary winding being connected with said boiler andbeing movable relatively to the primary winding, means for impressing anelectric charge on said boiler, and means connecting said movablesecondary winding'with said charge impressing means to regulate thelatter,

said charge impressing means being connected

